There are different types of 'devarim shebikdusha' (see Gittin 59b, for example), so I assume that you're only asking here about things that, due to their 'kedusha', require a minyan of ten Jewish men
–
MattJan 5 at 18:08

2 Answers
2

Perhaps someone can answer directly. Otherwise, this might help: Gather a list of things that are and a list of things that are not d'varim shebikdusha and see whether a rule can be figured out from the examples. I'm marking this answer "community wiki" so additions to it will be easier.

D'varim shebikdusha:

kadish (MB 55:2, from Mgila 23:2)

k'dusha (ditto)

bar'chu (ditto)

Torah-reading (ditto)

n'si'as kapayim of the kohanim (ditto)

chazaras hashatz (N.B.: MB 55:5 says it's considered such because it has k'dusha in it.)

Not:

Anything that we know does not require a minyan. (This is because any davar shebikdusha ipso facto requires a minyan.)

Halachic Dispute:

shlosh `esrei middot (the 13 Divine attributes): The Shulchan Aruch (Orach Chaim 565:5) says that they are d'varim shebikdusha. The source is the Rashba (Responsa 1:211), but in the printed editions, he says that they are liked'varim shebikdusha. The Tur says that they are not.

A davar shebekdusha (lit. thing done in holiness) is any ritual that requires a minyan to be done. It is called this because the Talmud (Megillah 23b) derives the requirement of a quorum of 10 for a 'minyan' from the verse (Leveticus 22:32) "Venikdashtim betoch benei yisrael" "And I will be sanctified in the midst of the Children of Israel". Venikdashti comes from the root of kedusha - holiness.

The mishna there gives these examples of things that require a minyan: